The present invention relates generally to fibrous mat products and, more particularly, to corrugated or pleated products taking the general form of a mat.
Various products are used as thermal insulators, sound insulators or as other more structurally supportive members, for example, in automotive applications. For example, so-called cross-lapped materials are fibrous mats formed of fibers oriented with their lengthwise dimension extending parallel to the plane of the mat. These materials often function as sound insulators, for example, in the dashboard or other areas of an automotive interior. Cross-lapped materials do not function well as pads or underlayments, for example, beneath a carpet because of their limited resilience or ability to compress. Often, various compressible foams will serve as supports or padding in those areas of a vehicle requiring increased cushioning.
Although various types of corrugated or pleated nonwoven fibrous materials are known, there is still a need to optimize the combined characteristics of sound absorption and resilience, especially in automotive applications. Examples are found in U.S. Pat. Nos. 4,576,853; 4,948,661; 4,950,439; 5,011,737; and 5,071,608. The prior pleated nonwoven materials may be used in a variety of specific applications, but are still in need of improvements relative to automotive applications. These applications may require high sound absorption characteristics and/or a high level of resilience or cushioning as well as other features.
Automotive textile products, such as carpets and body cloths, present another area of continued development. Automotive carpet products generally take two forms including nonwoven carpets and tufted carpets. In general, nonwoven carpets provide a lower cost alternative to tufted carpets. Thus, while tufted carpets typically provide a more plush and desirable surface within a vehicle interior or trunk, they also involve higher manufacturing costs which may be passed on to the consumer. Body cloths come in woven and nonwoven forms and may include items such as seat facings, upholstery and headliners. It would therefore be desirable to provide a lower cost automotive textile product having surface characteristics similar to a typical tufted carpet on knit velours.
The present invention generally provides a pleated or corrugated nonwoven product formed of natural or synthetic fibers, or combinations of both types of fibers. The product is initially formed as a pleated mat and may be formed in various thicknesses according to the intended application. In accordance with the invention, the fibers are oriented substantially vertically within each pleat of the product. It will be understood that the terms horizontal and vertical will be used relative to a mat of this invention which is laid out flat in a horizontal orientation. Of course, products formed in accordance with this invention may utilize pleated nonwoven mats ultimately oriented in any direction. In each case, however, the fibers forming each pleat extend in the direction of the pleat when viewed in transverse cross section. In conjunction with the type and size of the fibers, this results in a highly resilient and versatile mat suitable for a wide variety of uses and additional forming processes, such as thermoforming or compression forming.
Preferably, the pleated nonwoven product of this invention is formed by carding a plurality of fibers and then pleating the carded fibers with a pleating machine. More particularly, the fibers are carded onto a conveyor belt associated with the pleating machine such that the fibers extend in the machine direction or, in other words, direction of movement of the conveyor belt. The pleating machine orients the fibers perpendicularly, i.e., vertically, when forming the pleats. It is particularly desirable to have 90% of the fibers oriented substantially vertically within each pleat to optimize resilience at least in those cases in which the ultimate product will be used in a flat, generally uncontoured state, or in those applications in which the product is contoured in the machine direction. If the product will ultimately be contoured in a direction transverse to the machine direction, it is preferred that about 30% of the fibers extend in this transverse direction to help bind the product together during contouring. Various types of natural and synthetic fibers, as well as blends thereof, may be used to form the pleated products of this invention. Some examples of suitable fiber materials include nylon, polyethylene, polyester, polypropylene and cotton. The fibers may optionally include heat activated binders or other binders, or the pleats may be mechanically bound together during the pleating process, for example, using needles inserted transversely to the pleats and causing fibers of adjacent pleats to intertwine. Fiber blends and/or weights may be chosen to optimize resilience or sound absorption, or to optimize both of these characteristics. Natural fibers deliver better sound absorption capabilities, while pleated mats formed at least partially of synthetic, thermoplastic fibers may be thermoformed into desired three-dimensional shapes.
More specifically, pleated nonwoven products of the present invention are heated and molded under relatively low pressure, for example, to form various three-dimensionally shaped automotive interior parts, trunk liners and engine compartment liners. For example, a product of this invention may be molded and compressed in discrete areas to shape the product in the form of an automotive floor pan so that it may be used as a carpet or carpet pad. Relatively small presses, such as presses of less than ten tons, may be used for these molding or thermoforming processes. Typical insulator materials formed of cross-lapped fibers may require presses rated at 100 tons and above. Also, because fibers in typical insulators are randomly oriented, there may be a significant loss in acoustic absorption abilities during a molding or compression process. With the pleated product of this invention, the loss in acoustic properties generally should be less due to the physical characteristics of the product, i.e., the high loft and substantially vertical fiber orientation.
The present invention further contemplates a cost efficient, automotive textile product such as a carpet or body cloth preferably formed with the pleated nonwoven product or mat of the present invention. Specifically, the pleated nonwoven product may include a suitable backing for the desired end use on each of its major faces. Preferably, this backing may be a conventional back coating or backing used for automotive textiles, such as a backing that includes extruded polyethylene or polypropylene, or polymeric dispersions. Preferably after the backings are applied, the product is split centrally between the two backings to form mirror image textile products. The cut surfaces of the interior pleated layer simulate a tufted carpet surface. This procedure also results in a moldable or thermoformable automotive textile product capable of being produced at high speed. Moreover, in accordance with the invention, the resulting product may be selectively heated and compressed along its upper surface as necessitated by particular applications.
These and other objects, advantages and features of the invention will become more readily apparent to those of ordinary skill in the art upon review of the following detailed description taken in conjunction with the accompanying drawings.